Adaptive Structuration Theory (AST) is rapidly becoming an influential theoretical perspective in research on advanced information technologies. However, there still exists a paucity of methods to capture critical AST constructs. This paper describes the development of an instrument to capture the extent to which users of an advanced information technology believe they have appropriated its structures faithfully. The development of such instruments is considered critical if the theoretical base provided by AST is to be fully exploited in understanding the use of advanced information technologies. The development procedure, which occurred in the context of the use of an electronic meeting system, was carried out in three phases that began with initial item development and proceeded through an exploratory to a confirmatory phase. Three experiments, two in the exploratory phase and one in the confirmatory phase, were performed. In the final phase, structural equation modeling techniques were used to confirm the convergent, discriminant, and nomological validity of the resulting five-item scale.